Hardly ever used the DH, but the LNL is great at taking out medics with the splash coming off the heavies, and destroys entire sentry nests with both shots. In my opinion, those are the 2 most annoying things to get through.

Sodlier, he can one shot any light classes at point blank and close range, can 3 shot heavies at medium range and can destroy level 3 sentries in 2 shots.
Demoman...nothing really, if he has God-like aim he would do better by using the stock GL

Sodlier, he can one shot any light classes at point blank and close range, can 3 shot heavies at medium range and can destroy level 3 sentries in 2 shots.
Demoman...nothing really

A LnL demo can do the exact things you just said, yes, it takes extra time to reload, but it's deadly. Technically even more deadly because grenade launchers lack falloff, so you can be dealing 110-140 damage from any range.